fix: pasting in terminal buffer on windows #22566

Problem:
On Windows, pasting multiple lines on a terminal buffer cause all the
lines to appear on the same line, i.e., the line breaks are lost.

Cause:
Windows shells expect "\r\n" as line break but "terminal_paste" function
uses "\n".

Solution:
Use "\r\n" as line break for pasting in terminal buffer on Windows.

Note:
Although this issue was reported with powershell set as 'shell', it
occurs in cmd too.

Fixes #14621

src/nvim/terminal.c

@@ -723,7 +723,11 @@ void terminal_paste(long count, char **y_array, size_t y_size)
     for (size_t j = 0; j < y_size; j++) {
       if (j) {
         // terminate the previous line
+#ifdef MSWIN
+        terminal_send(curbuf->terminal, "\r\n", 2);
+#else
         terminal_send(curbuf->terminal, "\n", 1);
+#endif
       }
       size_t len = strlen(y_array[j]);
       if (len > buff_len) {